1. Field of the Invention
The present invention relates to a display device, and more particularly, to a power supply unit of a display device and a method thereof that can reduce frequency interference by electromagnetic interference (EMI).
2. Description of the Related Art
In recent years, in an informatization society, an importance of a display panel as a visual information transfer medium has been further emphasized. From now on, requirements such as lower power consumption, quantification, high-quality, and the like should be satisfied in order to occupy an important post.
The display panel may be classified into an emission type such as cathode ray tube (CRT), an electro luminescence (EL), a light emitting diode (LED), a vacuum fluorescent display (VFD), a field emission display (FED), a plasma display panel (PDP), and the like, which itself emits light and a non-emission type such as a liquid crystal display (LCD), which itself cannot emit light.
The display panel includes a driver for applying pulses to a plurality of electrodes. A power supply unit of the display device supplies power in order to operate the driver. In this case, AC input power is applied to the power supply unit of the display device.
At this time, in general, noise is generated in another electrical, electronic apparatus or system, such that noise is generated on an input terminal to which the power of the display device is applied through a power supply line.
The noise is known generically as electro-magnetic compatibility (EMC) and may be divided into electro-magnetic interference (EMI) and electro-magnetic susceptibility (EMS). EMI, that is, electro-magnetic interference represents a phenomenon in which needless electromagnetic waves generated from diversified electrical and electronic equipments cause electro-magnetic interference in other apparatuses and electro-magnetic susceptibility (EMS) represents electro-magnetic sensitivity of a predetermined apparatus to an external electro-magnetic environment.
Reinforcing electro-magnetic resistance of the display device itself by reducing EMI noise unnecessarily generated from the electrical and electronic apparatuses as possible and reducing electro-magnetic susceptibility to the external electro-magnetic environment meets electro-magnetic compatibility.
Herein, a lot of electro-magnetic interference (EMI) noise which is one of electro-magnetic compatibility (EMC) is generated by an influence of an external apparatus through an input line of an input terminal in the display device. The electro-magnetic interference noise deteriorates sound quality of a module of the display panel or induces a malfunction of a circuit formed in the module of the display panel.